Pinch closure bags, which may be used conveniently to store and transport such materials as grain, animal feed, fertilizer and other materials in powdered, granular or pellet form are typically made with multi-ply walls, the pinch closure being formed at one or both ends by folding an extension flap of one wall of the bag over the open end and adhesivey securing the flap to the outside ply of the other wall. For an example of a pinch closure bag, see Becker U.S. Pat. No. 3,203,620. Pinch closure bags are typically made so as to be resistant to tearing and breakage. Consequently, such bags may be difficult to open when, for example, a user wishes to remove the bag's contents.
Efforts have been made to provide convenient means for opening multi-ply pinch closure bags. For example, it has been proposed to incorporate extraneous components such as string and/or paper tabs as devices to assist in opening pinch closure bags. According to one such proposal, a paper tab would be inserted in the pinch closure between the adhesively secured extension flap and the outside wall of the bag. The tab would be arranged so that by pulling the tab, the portion of the flap overlying the tab would pull away from the remainder of the flap to form an opening for pouring. Such proposals, however, present a problem in that they require that a separate device be applied to the bag. Also, in the case of applying a tab to the pinch closure, there is the added disadvantage that the tab must be adhesively secured to the wall of the bag underlying the flap in order to provide a tight pinch closure. This may interfere with the pulling of the tab. If a weak adhesive were used for this purpose, it might unduly weaken the pinch closure.
Multi-ply pinch closure bags purportedly having an easy-open feature without the use of extraneous devices have also been proposed. U.S. Pat. No. 3,565,328 refers to the provision of a "tear tab" formed by a portion of the outer ply of the bag, as distinguished from a separate device. The patent also refers to a "tear strip" which is a separate paper strip adhesively secured under the closure flap to assist in opening the bag. This proposal, however, does not disclose or suggest an easy-open feature which takes full advantage of the strengths and weaknesses present in a pinch closure bag.